LTE Standard Module Series
EC20 R2.1 Mini PCIe Hardware Design
EC20_R2.1_Mini_PCIe_Hardware_Design 24 / 51
USIM_VDD
GND
USIM_RST
USIM_CLK
USIM_DATA
0R
0R
0R
100nF
GND
33pF
33pF 33pF
VCC
RST
CLK
IO
VPP
GND
GND
15K
USIM_VDD
(U)SIM Card Connector
Module
Figure 7: R Reference Circuit of (U)SIM Interface with a 6-pin (U)SIM Card Connector
In order to enhance the reliability and availability of the (U)SIM card in
customers’ applications, please
follow the criteria below in (U)SIM circuit design:
Keep placement of (U)SIM card connector to the module as close as possible. Keep the trace length
as less than 200mm as possible.
Keep (U)SIM card signals away from RF and power supply traces.
To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and
shield them with surrounded ground.
In order to offer good ESD protection, it is recommended to add a TVS diode with parasitic
capacitance not exceeding 15pF.
The 0
Ω resistors should be added in series between the module and the (U)SIM card connector so
as to facilitate debugging. The 33pF capacitors are used for filtering interference of EGSM900.
Please note that the (U)SIM peripheral circuit should be close to the (U)SIM card connector.
The pull-up resistor on USIM_DATA line can improve anti-jamming capability when long layout trace
and sensitive occasion are applied and should be placed close to the (U)SIM card connector.
3.9. PCM and I2C Interfaces
EC20 R2.1 Mini PCIe provides one Pulse Code Modulation (PCM) digital interface and one I2C interface.
The following table shows the pin definition of PCM and I2C interfaces that can be applied in audio codec
design.